Foam Composites with Multi-Stage Latex Emulsion Films

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Solution Overview

Problem

Pressure-sensitive adhesives (PSAs) on foamed or plasticized substrates experience degradation in peel or shear strength over time due to exposure to high temperatures or humidity, leading to loss of adhesive performance, which existing technologies fail to adequately address, especially since solvent-based adhesives are being phased out for environmental reasons.

Innovation Solution

A composite formed from a polymer foam or plasticized polymeric substrate and a latex polymer emulsion, where the emulsion is created through a multi-stage polymerization process, maintaining excellent retention of PSA properties over time by using a first stage polymer with a glass transition temperature below -20°C and additional ethylenically unsaturated monomers to swell and polymerize within the first stage polymer, incorporating plasticizers and tackifiers for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solvent-based adhesives are used to maintain adhesive performance on foamed or plasticized substrates, then adhesive performance is maintained, but environmental harm increases and solvent elimination is required

Engineering Contradiction:

Improveadhesive performanceVSAvoidenvironmental harm from solvents

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters of the adhesive by formulating an emulsion polymer containing specific functional monomers (carboxylic acid, hydroxyl, amine groups) that provide solvent-free adhesion mechanisms through hydrogen bonding and chemical interactions with the substrate

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite adhesive system combining emulsion polymer base resin with specific functional monomers and optional plasticizers, forming a multi-component emulsion polymer that achieves both environmental compliance and adhesive performance on challenging substrates

Inventive Principle:

Principle #40Composite materials

2Productivity

If emulsion PSAs are used to eliminate solvents and improve coating speed, then environmental performance improves and coating speed increases, but adhesive performance degrades over time due to aging

Engineering Contradiction:

Improvecoating speedVSAvoidadhesive performance on aging

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention modifies the emulsion polymer composition by incorporating functional monomers with specific glass transition temperatures and chemical groups that maintain adhesive flexibility and bonding capability during aging, preventing the performance degradation typical of conventional emulsion PSAs

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a multi-stage polymerization process that creates a stable emulsion polymer system with extended service life, effectively transforming the typically short-lived emulsion PSA into a durable adhesive that maintains performance over time

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If conventional emulsion polymerization is used to create water-insoluble latex polymer, then manufacturing simplicity is maintained, but adhesive performance on challenging substrates is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidadhesive performance on challenging substrates

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention segments the polymerization process into multiple stages, with each stage introducing specific functional monomers that contribute different adhesive properties, allowing complex performance requirements to be met through sequential, manageable manufacturing steps

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite emulsion polymer system combining base polymer resin with functional monomers (carboxylic acid, hydroxyl, amine groups) that provide enhanced adhesion to foamed and plasticized substrates while maintaining emulsion processability

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composite exhibits superior retention of adhesive properties on aging, outperforming comparative examples in peel force and failure mode, demonstrating improved durability and reliability on challenging substrates.

Implementation Method 1

dispersing in the first stage polymer, additional ethylenically unsaturated monomer comprising at least one monomer having at least two sites of alpha, beta-ethylenic unsaturation, whereby the additional monomer swells the first stage polymer

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS7723396B2Foam composites with emulsion polymer films

Publication Date: 2010.05.25 ROHM & HAAS CO

AI summary

This invention relates to composites comprising a substrate and a multi-stage latex polymer emulsion film.